"'The human we see in the mirror is made up of more microbes than human,' said Lita Proctor of the National Institutes of Health, who's leading the Human Microbiome Project."

Read that quote again. I am not exactly sure what she is trying to say. I think what she is meaning to say is that there are more microbe entities than human cells.
Or is she implying that pound for pound, there is more microbe mass than human mass in and on me?

Other sites validate the former. I have a hard time believing the latter.

The human body contains trillions of microorganisms--out numbering human cells by 10 to one. Because of their small size, however, microorganisms make up only about one to three percent of the body's mass but play a vital role in human health.

The human body contains trillions of microorganisms--out numbering human cells by 10 to one. Because of their small size, however, microorganisms make up only about one to three percent of the body's mass but play a vital role in human health.

The vast majority of the microbes in your body are in your large intestine (a large part of feces is dead and living bacteria); the rest live on body surfaces like skin and inside body cavities; your actual flesh very likely has no microbes in it, or very few (your immune system will kill any that do penetrate skin or intestinal walls), so it isn't really accurate to say that your body is made up of x% microbes.

If you take the "sack of space a human occupies" bacteria cells outnumber human cells by an order of magnitude.

However, all of this bacteria is technically outside the epidermis. A human is a tube within a tube, and your GI tract is protected by tissue similar to your skin. It would be disastrous if all that bacteria were allowed free entry into our body.

Edit: Much of the mentioned bacteria live on your skin and in your digestive tract.

The relationship with our bacteria is fascinating, and there is lots of neat research on the topic; from fecal transplants, to behavior modification.